River Honddu hit by 'major pollution' from slurry pit
A failed slurry lagoon has caused "major pollution" in Monmouthshire.
Natural Resources Wales (NRW) said the incident, near Abergavenny, is likely to have a "serious effect" on some rivers in south east Wales.
A "significant discharge" from the lagoon, which contained up to 450,000 litres (99,000 gallons) of slurry, went into a tributary of the River Honddu.
NRW officers are also assessing the impact on the River Monnow and River Wye.
Caroline Drayton, a team leader for NRW, said on Tuesday: "Protecting nature in Wales is our biggest priority and we have been carrying out pollution-prevention works to minimise the impact of this incident since this morning."
NRW is working closely with the Environment Agency in England to monitor the situation.